[NTG-pdftex] Docs for xpdf libraries or poppler?

Having cloned the source repository of poppler, I could not fail to notice that there is no API documentation that I could discern. Now PDFTeX obviously _has_ been able to make sense of the libraries. What source of information has been used for this? Key point is that I have to read some PDF files, process them at some rather shallow object level, and write out the results. So far, I have not even been able to figure out whether one of those libs would be suitable for that. Since PDFTeX does reading and writing of PDF (also of included PDF files), some basic facility would seem to be there? -- David Kastrup